An in-situ expandable gasket is required in certain applications where a clamping force cannot be applied to the gasket to form a seal. One such application is in a turbine compressor for providing cabin pressurization in an airplane. The compressor is constructed in multiple stages with the rotor blades detachably connected to the rotor leaving a small clearance between the base of each blade tip and the rotor disk. In the lower stages of compression where the temperature is relatively low an elastomeric polymer or rubber material may be placed into this space to form a seal. If the space is not sealed pressurized cabin air will escape through this space reducing efficiency. However, at the higher stages of compression where the temperature is relatively high and may rise to 400.degree. F. or higher, conventional elastomer or rubber gaskets deteriorate and cannot withstand the environment. Other conventional gasket materials which can endure higher temperatures including flexible graphite depend upon the application of a clamping force to form a seal. An expandable seal is desirable for applications which do not depend upon a clamping force to form a seal and particularly where the seal must be effective above ambient temperatures.